Energy efficiency is important to the design of refrigerators. Refrigerator parameters are typically optimized for testing/certification conditions to provide the best energy consumption as determined by various energy efficiency tests. However, the refrigeration cycle is affected by the home environment conditions in such a way that the refrigerator will consume more energy due to control parameters mismatch between the testing/certification conditions and the home environment conditions. Thus, there is a parameter detuning effect. The parameters that are affected are related to the time delay between the events of turning off the compressor and turning off the evaporator fan. The fan time delay, if not optimized, can lead to a drop in efficiency in the refrigeration operation. Once the compressor is off the time delay that controls the fan will re-circulate the air in the cavities through the evaporator to use its remaining cooling capacity. At some point, the evaporator temperature will be higher than the freezer and then it will stop cooling and warming up the freezer. Later on, the compressor will have to apply more energy to reduce the aforementioned temperature delta. Thus all of this will result in additional energy cost.
Although a thermocouple could potentially be used to avoid such an effect, introduction of a thermocouple increases cost and design complexity as the sensor and wiring would need to be added.
What is needed is a method to find an optimal time delay to turn off the evaporator fan of a refrigerator.